Submission #1203979

#TimeUsernameProblemLanguageResultExecution timeMemory
120397912345678The Ties That Guide Us (CEOI23_incursion)C++20
0 / 100
59 ms6548 KiB
#include <bits/stdc++.h> #include "incursion.h" using namespace std; const int nx=5e4+5; int n, c[nx], sz[nx], dp[nx], pa[nx], vs[nx]; vector<int> d[nx]; int dfssz(int u, int p) { sz[u]=1; for (auto v:d[u]) if (v!=p) sz[u]+=dfssz(v, u); return sz[u]; } void findcentroid(int u, int p, int rtsz) { for (auto v:d[u]) if (v!=p&&2*sz[v]>=rtsz) return findcentroid(v, u, rtsz); c[u]=1; c[p]=(2*sz[u]<=rtsz); pa[u]=p; pa[p]=u; } void dfs(int u, int p, int safe) { sz[u]=1; if (safe==u) dp[u]=1; if (u!=p) pa[u]=p; for (auto v:d[u]) if (v!=p&&!c[v]) dfs(v, u, safe), dp[u]|=dp[v], sz[u]+=sz[v]; } std::vector<int> mark(std::vector<std::pair<int, int>> F, int safe) { n=F.size()+1; for (int i=1; i<=n; i++) d[i].clear(), c[i]=dp[i]=sz[i]=0; for (auto [u, v]:F) d[u].push_back(v), d[v].push_back(u); findcentroid(1, 1, dfssz(1, 1)); for (int i=1; i<=n; i++) if (c[i]) dfs(i, i, safe); vector<int> res; for (int i=1; i<=n; i++) res.push_back(dp[i]); return res; } void locate(std::vector<std::pair<int, int>> F, int curr, int t) { n=F.size()+1; for (int i=1; i<=n; i++) d[i].clear(), c[i]=dp[i]=sz[i]=pa[i]=vs[i]=0; for (auto [u, v]:F) d[u].push_back(v), d[v].push_back(u); findcentroid(1, 1, dfssz(1, 1)); for (int i=1; i<=n; i++) if (c[i]) dfs(i, i, 0); while (1) { vs[curr]=1; if (t==0) t=visit(pa[curr]), curr=pa[curr]; else { vector<pair<int, int>> hv; for (auto v:d[curr]) if (v!=pa[curr]) hv.push_back({sz[v], v}); sort(hv.begin(), hv.end()); reverse(hv.begin(), hv.end()); int f=1; for (auto [sz, v]:hv) { if (vs[v]) continue; auto nt=visit(v); if (nt) { f=0; curr=v; t=nt; break; } visit(curr); } if (f) return; } } } /* 5 4 1 2 2 4 2 3 4 5 */
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